1. Field of the Invention
The present invention relates to a light-emitting device including a fluorescent body which absorbs excitation light from a light-emitting element and emits light having a wavelength different from that of the excitation light, and to an illumination apparatus and a display apparatus using the light-emitting device.
2. Description of the Background Art
Recently, a solid-state illumination technique (a semiconductor illumination technique) has been rapidly developed, which implements emission of light of white or other colors using a fluorescent body and a solid-state light-emitting element as an excitation light source for exciting the fluorescent body. Examples of such technique include a light-emitting device for obtaining pseudo-white light with a combination of a blue light-emitting element and a fluorescent body which absorbs blue light emitted from the blue light-emitting element and emits yellow light, and a light-emitting device for obtaining white light with a combination of an ultraviolet light-emitting element and red, green and blue fluorescent bodies which absorb ultraviolet light emitted from the ultraviolet light-emitting element and emit red, green and blue light, respectively.
The former light-emitting device has an inferior color rendering property because it includes less red component, but high light emission efficiency is expected since it has only a small loss regarding color conversion (a Stokes loss). The latter light-emitting device, on the other hand, has a good color rendering property.
Currently, the light-emitting device as such is generally formed as a shell-shaped type or a surface-mounted type. Referring to FIG. 17, a shell-shaped light-emitting device, for example, includes a lead frame 1706 on which a light-emitting element 1701 emitting excitation light for exciting a fluorescent body is mounted. One electrode of light-emitting element 1701 is electrically connected via a wire 1703a to lead frame 1706 which is electrically connected to one electrode terminal 1707a, and the other electrode of light-emitting element 1701 is electrically connected to the other electrode terminal 1707b via a wire 1703b. Light-emitting element 1701 is covered with a dispersion body 1705 in which a fluorescent body 1704 is dispersed. Blue excitation light emitted from a blue light-emitting element, for example, is partially absorbed by, for example, a YAG:Ce (yttrium-aluminium-garnet activated with cerium) fluorescent body covering the light-emitting element. Fluorescent light emitted from the fluorescent body excited with excitation light is propagated through dispersion body 1705 in which the fluorescent body is dispersed. Fluorescent light is transmitted through dispersion body 1705, and efficiently output to the outside with an exterior body 1709 having a convex surface to function as a lens (for example, see Japanese Patent Laying-Open No. 2000-286455). The light-emitting device having such structure, however, still has insufficient light output efficiency, and therefore development of a light-emitting device having higher light output efficiency has been desired.